SmartWay Applications for Drayage Trucks

Transcription

Texas
Transportation
Institute
Contract Number 582-8-90750
TEXAS TRANSPORTATION INSTITUTE
THE TEXAS A&M UNIVERSITY SYSTEM
COLLEGE STATION, TEXAS
Prepared In Cooperation With The
Texas Commission on Environmental Quality
And
U.S. Environmental Protection Agency
The preparation of this report was financed through grants from the U.S. Environmental Protection
Agency through the Texas Commission on Environmental Quality.
August 15, 2009
by
Monica Beard-Raymond
Assistant Research Scientist
Center for Air Quality Studies, Texas Transportation Institute
Tel.: (512) 467-0946 Email: [email protected]
Mohamadreza Farzaneh, Ph.D.
Carlos Duran
Graduate Research Assistant
Research and Implementation Division, Texas Transportation Institute
Josias Zietsman, Ph.D., P.E.*
Center Director
Doh-Won Lee, Ph.D.
and
Jeremy Johnson.
Associate Research Specialist
* Principal Investigator and Corresponding Author
TABLE OF CONTENTS
1. 2. Executive Summary ........................................................................................................... 4 Background Information................................................................................................... 6 Drayage Operations ................................................................................................................. 6 Drayage Border Crossings ....................................................................................................... 9 Drayage Emissions and SmartWay Strategies ....................................................................... 11 In-Use Emissions Measurement ............................................................................................ 12 Data Analysis Using Methodology from EPA’s MOVES Model ......................................... 15 3. Identification and Selection of SmartWay Strategies ................................................... 17 Criteria for SmartWay Strategy Selection ............................................................................. 17 Cost of Strategy.................................................................................................................. 17 Emissions Reduced ............................................................................................................ 18 Fuel Consumption .............................................................................................................. 18 Applicability to Drayage Border Operations ..................................................................... 19 Maintenance ....................................................................................................................... 20 Driver Comfort................................................................................................................... 20 Assessment of SmartWay Strategies ..................................................................................... 20 Strategy Selection for Border Drayage Operations ............................................................... 22 4. In-Use Testing: Preparation and Procedures ................................................................ 24 Preparation for In-use Testing ............................................................................................... 24 Testing Location and Traffic Management Plan ............................................................... 24 SmartWay Strategies .......................................................................................................... 25 Selection of Drayage Trucks .............................................................................................. 26 Test Drive Cycles............................................................................................................... 27 In-Use Testing ........................................................................................................................ 28 Testing Equipment ............................................................................................................. 28 Testing Procedures ............................................................................................................. 30 5. Results ................................................................................................................................... 32 Modal Emissions .................................................................................................................... 32 Impact Analysis ..................................................................................................................... 35 6. Concluding Remarks ....................................................................................................... 39 7. Recommendations ............................................................................................................ 41 8. Acknowledgements .......................................................................................................... 42 Appendix A ............................................................................................................................... 43 Appendix B ............................................................................................................................... 44 3
1. EXECUTIVE SUMMARY
Drayage trucks operating daily across the border between the U.S. and Mexico can be a
significant source of emissions, which negatively impact air quality. The U.S. Environmental
Protection Agency’s (EPA) SmartWay Transport Partnership program helps to reduce fuel
usage and emissions from freight operations through the use of technologies and best practices.
SmartWay strategies are primarily touted for long-haul trucking and not the short haul
operations found in drayage vehicles. This project tests the applicability of three SmartWay
strategies (use of lighter trailers, modified driving behavior, and the use of diesel oxidation
catalysts) for border drayage operations.
This project studies the availability, use, and effect of SmartWay technologies on emissions
and fuel use from drayage trucks traveling between the U.S. and Mexico. The overall goal of
this project is to provide a broad range of stakeholders (drayage truck owners and operators
and public and private sector organizations) with information on effective SmartWay
technologies for drayage trucks.
The study focuses on the El Paso-Ciudad Juárez border area. The area has a significant drayage
truck circulation that is typical of other drayage activities along the U.S./Mexico border. El
Paso is currently categorized as nonattainment for particulate matter (PM10), and bordercrossing activities directly impact El Paso’s air quality and attainment status.
Three different SmartWay strategies were tested and evaluated for their emissions and fuel
consumption impacts. Based on their costs, potential emissions benefits and applicability to
drayage operations, the study tested the emissions and fuel economy performance of lighter
trailers, driving behavior, and diesel oxidation catalysts (DOCs). Five drayage trucks were
provided by two local trucking companies (Fletes Sotelo and STIL) for the testing. These
trucks, representing common makes and models were tested with portable emissions
measurement systems (PEMS) units before and after implementation of a SmartWay strategy.
PEMS collected second-by-second emissions of oxides of nitrogen (NOx), hydrocarbons (HC),
carbon monoxide (CO), PM, and carbon dioxide (CO2). CO2 emissions served as a proxy for
fuel consumption testing.
This project required a funding match from another source – for this, testing of a fuel
combustion enhancer from Carbon Chain Technologies Limited was performed in addition to
the emissions measurement of the three selected SmartWay technologies. The company’s 2ct®
product was tested in light duty gasoline vehicles and heavy-duty diesel vehicles for fuel
economy and emissions, and may have potential for future applicability for emissions
reduction efforts and for Smartway. The abstract from this project is included in Appendix B.
The Texas Transportation Institute (TTI) compared the emissions results from baseline tests
with results from tests performed with a SmartWay strategy deployed. The EPA’s Motor
Vehicle Emissions Simulator (MOVES) model approach was employed, which uses vehiclespecific power (VSP) and operating mode bins to evaluate emissions.
4
The research team developed and implemented a data collection and data analysis
methodology based on the EPA’s MOVES model’s analysis framework. The methodology is
based on the concept of second-by-second modal emissions rates based on VSP. Driving
patterns were developed to cover broad range of drayage trucks operational modes. The
methodology significantly reduces the duration of the data collection effort compared to using
regular drive cycles.
The gaseous (CO2, CO, NOx, and total HC [THC]) and PM emissions rates were measured
using two PEMS units. Using the previously-mentioned VSP-based approach, the collected
emissions data were grouped into operating mode bins according to criteria used in EPA’s
MOVES model and average emissions rates for each bin were calculated from all the
observations that fall within that operating mode bin.
The research team found that the operating mode bins provide satisfactory estimates for
drayage operation at the U.S./Mexico border. A cycle-based analysis was performed using the
drayage operation speed profiles that were collected using a Global Positioning System (GPS)
technology. The results show that DOCs provide major THC and CO reduction benefits for
drayage operations. Lightweight trailers and Eco Driving were also found to decrease CO and
THC emissions moderately. Only Eco Driving appeared to have a positive impact on CO2, fuel
consumption, and NOx emissions. All the investigated strategies resulted in lowering PM
emissions compared to the baseline.
5
2. BACKGROUND INFORMATION
Vehicle emissions measurement is a highly technical endeavor. This section provides the
background information necessary to understand the significance of the project and the
reasoning behind the project team’s approach and methodology for evaluating the effectiveness
of key SmartWay strategies on drayage operations. The section on drayage operations
highlights why understanding and mitigating these emissions are important. The remaining
sections on border crossings, SmartWay strategies, in-use testing, and EPA’s MOVES model
methodology all serve to provide the background information necessary to understand the
scientific approach underlying the project’s methodology.
DRAYAGE OPERATIONS
In 2007, more than $347 billion worth of goods were traded between the U.S. and Mexico. 1
Most of this trade is conducted through container transport across the international boundary
between the two countries via truck or rail. These goods must enter or exit the U.S. through
one of 29 commercial truck ports of entry (POE) along the U.S.’s southern border.
International shipments crossing the border via truck have a significant impact on both the
economy and the environment in the areas where the goods cross.
An estimated 90 percent of truck traffic between the U.S. and Mexico is comprised of drayage
trucks used for short haul trucking. 2 With few exceptions, Mexico-domiciled carriers are
limited to the commercial zone that generally extends from 3-to-25 miles north of the border.
This results in the vast majority of shipments crossing the border by short hauls, in which
Mexican cargo destined for the U.S. is dropped off near the border, loaded onto a drayage
truck, taken across the border and then unloaded at a location within the U.S. commercial zone.
The border crossing at El Paso, Texas and Ciudad Juárez, Mexico is one of the busiest border
crossings in the state. Ciudad Juárez is El Paso’s sister city across the border and is the largest
city in the state of Chihuahua and the fifth largest city in Mexico. The metropolitan area of
Ciudad Juárez and El Paso comprises of more than 2.2 million people, making it the largest binational metropolitan area in the world. 3 El Paso is currently the sixth largest city in Texas and
the 21st largest city in the U.S. In 2007, more than 780,000 trucks from Mexico entered the
U.S. from one of El Paso’s two international bridges for commercial trade. 4
Following the implementation of the North American Free Trade Agreement (NAFTA), trade
between the U.S. and Mexico increased substantially. Northbound commercial movements
through the Ciudad Juárez-El Paso gateways have continuously risen over the past 10 years. 5
The overall growth of northbound commercial movements between Ciudad Juárez and El Paso
1
U.S. Census Bureau. Top Ten Countries with which U.S. Trades, http://www.census.gov/foreigntrade/top/dst/2007/12/balance.html, accessed December 2008.
2
Mexican Truck Idling Emissions at the El Paso-Ciudad Juarez Border Location. Texas Transportation Institute,
The Texas A&M University System, College Station, TX, November 2005.
3
El Paso. El Paso Information and Links, http://www.elpasoinfo.com/, accessed November 2008.
4
Texas A&M International University, Texas Center for Border Economic and Enterprise Development.
http://texascenter.tamiu.edu/texcen_services/truck_crossings.asp?framepg=datatruck, accessed November 2008.
5
US Customs and Border Protection, http://www.cbp.gov/, accessed October 2008.
6
increased by more than 153,000 crossings over the past decade, as Figure 1 shows. The effect
of the economic slowdown is seen in a significant reduction in the number of trucks crossing
the US-Mexico border at the ports of El Paso in 2008.
More than 40 percent of Mexican exports can be traced to maquiladoras. 6 Maquiladoras are
foreign owned factories in Mexico that import raw materials, assemble them into products and
then export the manufactured goods back into the originating country (typically the U.S.).
Many of these manufacturing facilities receive raw materials from the U.S. and ship assembled
goods back across the U.S./Mexico border in significant volumes.
Figure 1. Incoming Truck Movements through El Paso, TX.
Number of Turcks (Thousands)
800
750
700
650
600
550
500
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Year
SOURCE: U.S. Department of Transportation, Research and Innovative Technology Administration,
Bureau of Transportation Statistics, Border Crossing/Entry, accessed October 2009
Despite much controversy, the U.S. has made proposals and plans for opening up the border to
Mexican trucks and allowing them to operate beyond the U.S. commercial zone. If the U.S.
border is opened to Mexican trucks, then current drayage operations could be altered
significantly. However, the scale and impact of this potential change is unknown. A report
evaluating the safety performance of Mexican trucks found insufficient Mexican participation
in the study, which may indicate that significant barriers exist beyond legally opening the
border for Mexican long-haul trucking in the U.S. 7 More definitive studies on the safety
implications of opening the southern border are underway, and it will be a minimum of one
year before the federal government will make a decision regarding whether Mexican trucks
will be allowed to operate within the interior U.S.
6
Dallas Federal Reserve. NAFTA and Maquiladoras: Is Growth Connected?,
http://www.dallasfed.org/research/border/tbe_gruben.html, accessed November 2008.
7
Downey III, Mortimer L., et. al. Independent Evaluation Panel Report to the U.S. Secretary of Transportation:
U.S.-Mexico Cross-Border Trucking Demonstration Project. October 31, 2008.
http://www.dot.gov/affairs/PanelReport.pdf, accessed November 2008.
7
Drayage trucks are typically older and less well maintained than long-haul trucks and therefore
can emit more pollution than their newer, long-haul counterparts 8 . Figure 2 shows the age
distribution of a sample of drayage trucks and the Texas fleet age distribution from registration
data. The drayage fleet age distribution belongs to Laredo border crossing and is based on a
border survey performed by TTI in 2006. It is expected that drayage fleet operating in the El
Paso region would have similar characteristics. As shown in Figure 2, approximately 55
percent of U.S. class 8b trucks registered in Texas in 2006 were newer than model year 2000
(with 85 percent newer than 1995) while only 10 percent of drayage fleet was newer than 2000
( and only 40 percent newer than 1995).
Figure 2. Age Distribution of Drayage Fleet and Long-Haul Fleet Trucks.
14%
12%
Proportion
10%
8%
6%
4%
2%
0%
Model Year
18%
16%
Proportion
14%
12%
10%
8%
6%
4%
2%
20
05
20
03
20
01
19
99
19
97
19
95
19
93
19
91
19
89
19
87
0%
Model year
8
Note: The research team could not find any other documentation of the maintenance level of the drayage fleet at
El Paso; however, the field observations by the research team indicated a poor level of maintenance compared to
other long-haul trucks.
8
A drayage truck’s typical stop-and-go driving cycle contributes to increased emissions with
more frequent stops and idling during border crossing times and load/unload periods. Drayage
trucks typically make daily trips in fewer than 200 miles and do not idle overnight. 9 While
drayage fleets are primarily comprised of small carriers, there are several carriers that dominate
the El Paso-Juárez border crossing. A prior TTI study surveyed more than 200 different
carriers crossing the border, but found that 16 account for approximately half of the total
trips. 10 Presumably, this translates into a rather consistent fleet of trucks crossing the border.
DRAYAGE BORDER CROSSINGS
El Paso is home to two of the largest commercial POEs along the U.S.’s southern border – the
Bridge of the Americas (BOTA) and the Ysleta-Zaragoza Bridge. El Paso is second only to
Laredo in the number of northbound truck shipments crossing along the U.S.’s southern
border. 11 While the Ysleta-Zaragoza crossing has longer hours of operation, the facility
charges a toll (approximately $10), and therefore many drayage operators prefer the BOTA.
A previous TTI study evaluated drayage idling at both bridges. Outlined in Table 1, the study
found that average percentage of time spent in idling and creep idling were in excess of 60
percent for both bridges. Creep idling or “queue” idling refers to the type of idling that occurs
when trucks waiting in long lines idle and move very slowly. Normal type of idling is in excess
of creep idling. This normal idling is very significant because creep idling is very difficult to
control and most idle control technologies are not effective for creep idling applications. The
Ysleta-Zaragoza crossing had higher travel and idling times than the BOTA crossing. The
average normal idle time per truck per crossing for the BOTA was 9.5 minutes and 21.5
minutes for the Yselta-Zaragoza crossing.
9
U.S. EPA. DrayFLEET: EPA SmartWay Drayage Activity and Emissions Model and Case Studies,
http://www.epa.gov/smartway/transport/documents/drayage/final-dray-fleet-report.pdf, accessed November 2008.
10
11
Bureau of Transportation Statistics. U.S. Border Crossings, http://www.transtats.bts.gov/BorderCrossing.aspx,
accessed October 2008.
9
Table 1. Summary of Travel Time, Normal Idling and Creep Idling.
Section
1- Mexican customs
booth to U.S.
primary inspection
station
2- Within U.S.
federal compound
3- From federal
compound to state
Border Safety
Inspection Facility
(BSIF) exit
Total
Travel
Time
(min)
BOTA
%
Normal
Idle
%
Creep
Idle
Ysleta-Zaragoza
Travel
%
%
Time
Normal
Creep
(min)
Idle
Idle
8.5
41%
18%
11.1
36%
13%
8.2
62%
13%
23.0
75%
8%
4.2
13%
29%
-
-
-
21.0
45%
18%
34.2
63%
9%
Source: Mexican Truck Idling Emissions at the El Paso-Ciudad Juárez Border Location. Texas Transportation
Institute, The Texas A&M University System, College Station, TX, November 2005.
TTI’s study also examined idling times during peak and off-peak periods and for Free and
Secure Trade (FAST) program and non-FAST trucks. The FAST program provides carriers an
expedited border crossing in exchange for increased security measures. Table 2 provides a
summary of idling and volume per travel mode.
Table 2. Idling, Creep Idling and Volumes per Travel Mode.
Travel
Mode
Offpeak/FAST
Offpeak/NonFAST
Peak/FAST
Peak/NonFAST
BOTA
Normal
idle time
(min)
Creep
idle time
(min)
90
4.1
4.2
89
7.1
2.3
420
16.5
3.7
432
33.9*
5.1
140
8.5
3.2
141
20.8
1.7
651
9.5*
5.2
683
11.4*
2.4*
Volume
(veh/day)
Ysleta-Zaragoza
Normal
Creep
Volume
idle time
idle time
(veh/day)
(min)
(min)
* These values are adjusted by providing different weights because only 1 percent of the cases represent
extensively long crossing times (commonly from secondary inspections).
Source: Mexican Truck Idling Emissions at the El Paso-Ciudad Juárez Border Location. Texas Transportation
Institute, The Texas A&M University System, College Station, TX, November 2005.
10
Contrary to expectations, the table suggests that FAST participation does not consistently
reduce idle times. While normal idling was reduced for FAST participants at the BOTA and for
off-peak idling at the Ysleta-Zaragoza crossing, the idling times actually increased for FAST
members during peak times at the Ysleta-Zaragoza crossing. For creep idling, FAST
participants had lower creep idling times compared to their non-FAST counterparts except
during the off-peak period at the BOTA crossing.
The table also indicates that peak periods do not consistently increase idling times. For FAST
program participants, normal idling increased during peak periods but creep idling was reduced
at the Ysleta-Zaragoza crossing. For non-FAST trucks, peak period idling was reduced for
normal idling and for creep idling at the Yselta-Zaragoza crossing. However, creep idling
increased during peak periods at the BOTA.
Together, these findings indicate that other factors may significantly affect truck idling times.
However, consistency could be found in that for almost every category for each crossing,
normal idling occurred for longer durations than creep idling. Also noteworthy is the
observation that truck volumes were fairly similar between the two crossings with slightly
more trucks utilizing the Ysleta-Zaragoza crossing presumably because of its longer operating
hours.
DRAYAGE EMISSIONS AND SMARTWAY STRATEGIES
Emissions from drayage traffic crossing the border contributes to El Paso’s air quality issues.
A TTI study found that drayage idling alone at the border produced 24 tons/year of NOx and
600 pounds/year of PM. 12 These emissions account for a small percentage of the overall
onroad emissions budget (which is a ceiling on emissions levels used in conformity
determination), yet generate a high concentration of emissions in a small geographic area and
do not include the whole of emissions contributed by drayage truck operations. El Paso is in
moderate nonattainment for PM-10 and was just recently found to be in compliance with CO.
Reducing idling and emissions from drayage trucks can help mitigate these emissions.
Fortunately, there are many options for reducing idling and emissions from heavy-duty diesel
trucks. EPA’s SmartWay Transport Partnership Program outlines options for reducing
greenhouse gas (GHG) emissions and air pollution from freight movement. It should be noted
that not all strategies uniformly decrease all emissions – some may decrease only certain types
of emissions and may even increase certain others. Strategies can be divided into the following
categories.
•
Engine, tire and truck modifications- low rolling resistance tires, auto-tire inflation,
aerodynamic improvements, low-viscosity lubricants, lighter tractors and trailers,
and SmartWay certified trailers.
•
Idle reduction technologies- bunker heaters, auxiliary power units (APUs),
automatic shut down and start up systems, and electrified parking spaces.
12
11
•
Diesel retrofit and advanced technologies- hybrid power-train technology, DOC,
diesel particulate filter (DPF), selective catalytic reduction (SCR), and replacing
engine and trucks with newer models complying with new emission certification
standards.
•
Cleaner fuels- compressed natural gas (CNG) and biodiesel.
•
Operational strategies- speed reduction, driver education, and improved freight
logistics.
SmartWay certified trailers employ a combination of strategies to reduce fuel consumption and
emissions, and contain components that overlap with the more itemized options on the list.
SmartWay provides a list of specific model trailers on their website. These certified trailers
include:
•
side skirts;
•
weight-saving technologies (optional);
•
gap reducer on the front or trailer tails (either extenders or boat tails); and
•
options for low-rolling resistance tires (single wide or dual). Weight-saving
aluminum wheels are optional.
SmartWay also has a certification program for tractors that requires a host of aerodynamic
devices, a 2007 or later model year engine, and an idle control device. For drayage operations,
this strategy would often be incorporated as a truck replacement strategy.
IN-USE EMISSIONS MEASUREMENT
Direct vehicle emissions measurements are either performed in a laboratory with a chassis or
engine dynamometer or occur during in-use operation with a PEMS. This project used PEMS
to test three different SmartWay strategies on five drayage trucks. CO2 emissions are used as a
proxy for fuel consumption. EPA and the Intergovernmental Panel on Climate Change (IPCC)
estimate that 99 percent of carbon in the fuel is oxidized, which demonstrates that CO2
emissions are appropriate for estimating fuel consumption. 13
PEMS has a secure foothold within transportation and air quality science. PEMS testing has
been used since the late 1990’s for providing real-world emissions information. Several studies
have confirmed the validity and reliability of PEMS testing, including EPA’s large-scale study
of light-duty vehicles in Kansas City, which found that PEMS compared favorably to the
chassis dyno testing of 480 vehicles. 14 Both EPA and the California Air Resources Board
(CARB) employ PEMS testing for in-use compliance of heavy-duty diesel vehicles for all
13
U.S. EPA. Emission Facts: Average Carbon Dioxide Emissions Resulting from Gasoline and Diesel Fuel,
http://www.epa.gov/otaq/climate/420f05001.htm, accessed August, 2009.
14
T. Younglove, G. Scora, and M. Barth. Designing On-road Vehicle Test Programs for Effective Vehicle
Emission Model Development. Transportation Research Record: Journal of the Transportation Research Board,
No.1941, 2005, pp. 51-59.
12
criteria pollutants except PM. 15, 16 PEMS has several advantages for emissions measurement,
including the technology’s ability to:
• provide accurate data cost-effectively;
• capture real-world emissions;
• can supply data on emissions, activity and environmental data simultaneously 17 ;
• test vehicles at any location, including where the emissions normally occur; and
• test large vehicles more easily.
EPA’s In-Use Testing Program sets guidelines for PEMS testing, which are provided in 40
CFR Part 1065, Subpart J. The regulations provide exhaust flow measurement specifications,
establish PEMS performance standards, and outline the procedures for system calibration,
verification, and conducting the actual PEMS test. The regulations also specify the
instrumentation components that are acceptable for PEMS emissions measurement. Table 3
outlines the instrument system for each pollutant, along with a column for TTI’s SEMTECHDS unit.
Table 3: PEMS Emissions Measurement Instruments
Pollutant
EPA’s Acceptable
Instrument for
Measurement
NOx
Chemiluminescence
detector (CLD) or nondispersive ultra-violet
detector (NDUV)
CO
Non-dispersive infrared
detector (NDIR)
NMHC*
Flame ionization detector
(FID)
Description
NOx is typically measured as the
sum of nitrous oxide (NO) and
NO2. CLDs convert NO2 to NO
and measure NO emissions. NDUV
measures NO and NO2 directly.
Infra-red light is pulsed through a
gas sample to alternately detect CO
and CO2 concentrations.
FID is a gas detector used to
measure HC concentrations.
TTI’s
SEMTECHDS System 18
NDUV
NDIR
FID**
* NMHC: Non-Methane Hydrocarbons
** The SEMTECH-DS FID provides Total Hydrocarbon concentrations.
PM measurements have been more of a challenge for PEMS and thus have been delayed for
use in the compliance program. The pilot program for PEMS PM measurement for compliance
purposes and the determination of accuracy margins for PM are currently underway. Some
15
On-Road Heavy-Duty Diesel Engine In-Use Compliance Program Homepage. California Environmental
Protection Agency Air Resource Board. Updated July 18, 2007.
http://www.arb.ca.gov/msprog/onroadhd/hdiut.htm, accessed August, 2009.
16
Heavy Trucks, Buses, and Engines Homepage. U. S. Environmental Protection Agency.
http://www.epa.gov/otaq/hd-hwy.htm, accessed on August, 2009.
17
Note: The PEMS unit uses in this study, SEMTECH-DS, is equipped with GPS and engine data recording
capability.
18
U.S. Environmental Protection Agency. In-Use Testing Program for Heavy-Duty Diesel Engines and Vehicles.
Technical Support Document, EPA420-R-05-006, June 2005.
13
PEMS units, such as TTI’s Axion system manufactured by Clean Air Technologies
International, do measure PM mass through light scattering detection technology. While these
systems are not yet approved for in-use compliance purposes for PM measurement, they are
commonly used in academic research.
A central advantage of PEMS is its ability to characterize in-use emissions. The systems
capture second-by-second emissions data, operational and environmental data simultaneously,
which allows for emissions studies to more closely link vehicle operations and road conditions
to emissions behavior. Several PEMS studies have demonstrated that the importance of vehicle
operation is a crucial component of emissions behavior.
TTI has conducted more than a dozen PEMS studies, some of which have challenged previous
assumptions and provided interesting insights. For example, a study on Mexican trucks found
that the tested Mexican trucks did not typically have elevated emissions when compared to
their U.S. counterparts from same model year. 19 A separate study examining Mexican trucks
emissions using various types of fuel also found that using Mexican fuel (PEMEX), which has
higher sulfur levels than ultra-low sulfur diesel (ULSD) fuel, did not translate into the expected
higher PM emissions or increased air toxic levels. 20
One important aspect of PEMS testing is the drive cycle of the vehicle. Drive patterns differ by
vehicle type, which greatly affects emissions. 21 While some tests have been conducted in
traffic under real-world conditions, this method of testing can be particularly difficult for
heavy-duty diesel vehicles due to the sensitive nature of the PEMS equipment. 22 An alternative
option is to conduct testing on a track or in a low traffic area with a pre-determined drive cycle.
Drive cycles are often created to mirror typical driving patterns by incorporating GPS data
collected over a period of time.
Using a track with a pre-determined drive cycle provides three primary advantages. Predetermined drive cycles reflect averaged driving patterns instead of reflecting the conditions of
a single testing period that may prove to be an atypical day. A developed drive cycle can also
allow for the replication of tests easily. Under real-world conditions, the timing of lights and
flow of traffic would be a few factors that would make comparisons between tests difficult. In
this study, traffic was diverted from one lane of a low-traffic roadway with no traffic lights to
eliminate inconsistencies between tests.
19
J. Zietsman J. Villa, T. Forrest, and J. Storey. Mexican Truck Idling Emissions at the El Paso - Ciudad Juarez
Border Location. Southwest Region University Transportation Center, Report No. SWUTC/05/473700-00033-1.
The Texas A&M University System, College Station, Texas, November 2005.
20
J. Zietsman, M. Farzaneh, J. Storey, J. Villa, M. Ojah, D. Lee, and P. Bella. Emissions of Mexican-Domiciled
Heavy-Duty Diesel Trucks Using Alternative Fuels. Texas Transportation Institute, The Texas A&M University
System, College Station, Texas, October 2007.
21
M. Andre, R. Joumard, R. Vidon, P. Tassel, and P. Perret. Real-World European Driving Cycles, for Measuring
Pollutant Emissions from High- and Low-Powered Cars. Atmospheric Environment, Vol.40, 2006, pp. 5944-5953.
22
14
Probably the most important advantage of a developed drive cycle is the ability to test vehicles
under a more complete variety of driving behavior and conditions. High-powered events are
particularly recommended for testing because there is a general lack of emissions data for these
high emitting events. One study recommends the use of air conditioning and a series of
accelerations up to freeway speed at 50 percent throttle, 75 percent throttle, 90 percent throttle,
and wide-open throttle to ensure that even atypical events are measured. 23 Many TTI studies
have employed the use of drive cycles to ensure data quality and account for the full range of
vehicle operation. 24, 25
DATA ANALYSIS USING METHODOLOGY FROM EPA’S MOVES MODEL
This project utilizes some of the concepts and methodologies used in EPA’s MOVES model to
analyze emissions data. The MOVES model will replace EPA’s MOBILE 6.2 model for air
quality planning, emissions inventories and regulatory efforts. By using the MOVES
methodology framework to analyze data, this project is better able to analyze the operational
characteristics of emissions data according to an established analysis protocol. The local data
needs for MOVES are also significant and the results from this study can be used to enhance
localized inputs into the MOVES model for the El Paso border area.
The MOVES model better characterizes in-use emissions by using second-by-second
emissions rates that account for a vehicle’s operating modes. This enables the model to provide
a finer scale of analysis for use at the local level. MOVES incorporates VSP to capture modal
emissions. EPA defines the term as “power per unit mass of the source” and is characterized in
Equation 1. 26, 27 VSP accounts for the forces a vehicle must overcome when operating on the
road, including acceleration, road grade, tire rolling resistance, and aerodynamic drag. For
example, fast accelerations or driving up a steep hill would have a higher VSP bin, rather than
coasting downhill.
A × u + B × u2 + C × u3 + M × u × a
(1)
VSP =
M
Where:
u is instantaneous speed of vehicle in m/s;
a is instantaneous acceleration of vehicle in m/s2;
A is a rolling resistance term;
23
T. Younglove, G. Scora, and M. Barth. Designing On-road Vehicle Test Programs for Effective Vehicle
Emission Model Development. Transportation Research Record: Journal of the Transportation Research Board,
No.1941, 2005, pp. 51-59.
24
25
J. Zietsman, M. Farzaneh, J. Storey, J. Villa, M. Ojah, D. Lee, and P. Bella. Emissions of Mexican-Domiciled
Heavy-Duty Diesel Trucks Using Alternative Fuels. Texas Transportation Institute, The Texas A&M University
System, College Station, Texas, October 2007.
26
Draft Design and Implementation Plan for EPA’s Multi-Scale Motor Vehicle and Equipment Emission System
(MOVES). EPA420-P-02-006, U.S. Environmental Protection Agency, October 2002.
27
Draft Software Design and Reference Manual: Motor Vehicle Emission Simulator Highway Vehicle
Implementation (MOVES-HVI) Demonstration Version. MOVES Homepage. U.S. Environmental Protection
Agency, February 2007. Available online at: http://www.epa.gov/otaq/ngm.htm.
15
B is rotating resistance term;
C is a drag term; and
M is the vehicle’s weight in metric tonne.
VSP is normalized by mass and placed into bins. There are 23 bins based on VSP and
instantaneous speed. Table 4 shows the MOVES operating bins. A vehicle operating over a
drive cycle would then spend different times in different bins depending on operation.
Table 4. MOVES Operating Mode Bin Definitions for Running Emissions.
Braking (Bin 0)
Idle (Bin 1)
Instantaneous Speed
(mph)
Instantaneous VSP
(kW/tonne)
<0
0 to 3
3 to 6
6 to 9
9 to 12
12 and greater
12 to 18
18 to 24
24 to 30
30 and greater
6 to 12
<6
0-25
25-50
Bin 11
Bin 12
Bin 13
Bin 14
Bin 15
Bin 16
Bin 21
Bin 22
Bin 23
Bin 24
Bin 25
Bin 27
Bin 28
Bin 29
Bin 30
> 50
Bin 37
Bin 38
Bin 39
Bin 40
Bin 35
Bin 33
The VSP and bin approach is expected to be a clear indicator of emissions and provide
the needed flexibility to provide analysis at meso and microscales of analysis. 28
MOVES’ more disaggregated methodology is expected to more precisely estimate
emissions based on the local activity data available. This approach is a better fit for
incorporating operational data provided by in-use emissions testing.
28
C. Lindhjem, A. Pollack., R. Slott., and R. Sawyer. Analysis of EPA’s Draft Plan for Emissions Modeling in
MOVES and MOVES GHG. CRC Project E-68. Final Report Prepared for Coordinating Research Council, Inc.
Environ, Novato, California, May 2004.
16
3. IDENTIFICATION AND SELECTION OF SMARTWAY
STRATEGIES
As discussed in the background section on SmartWay strategies, there are several approaches
recommended by the EPA program for reducing emissions and fuel usage from the freight
sector. These strategies have been primarily focused on long-haul operations and are largely
unevaluated for their applicability to the short-haul operations used by drayage fleets.
There are dozens of approaches for reducing emissions and fuel usage from freight movement.
However, this project chose three key strategies for evaluation. With comments and
recommendations from the Texas Commission on Environmental Quality (TCEQ) and EPA’s
SmartWay Transport program, the list of SmartWay strategies was reduced to the following
approaches: DOCs, driver behavior, and lighter trailers.
The selected strategies were chosen based on a series of criteria. The sections below describe
the criteria used for selection and how individual strategies faired when evaluated by those
strategies.
CRITERIA FOR SMARTWAY STRATEGY SELECTION
There is no silver bullet solution to emissions reductions from heavy-duty trucks. Every option
will have benefits and drawbacks depending on the situation and objective. Selecting the
appropriate strategy will depend on a variety of factors. Key factors affecting strategy selection
are outlined in the following sections along with a discussion about how this factor would
apply to drayage trucks in the El Paso area.
Cost of Strategy
The cost of a strategy typically varies with the application. Some strategies, such as truck
replacement, are very expensive. Other strategies, such as speed reduction, do not result in
direct expenditures, but may affect trip travel times and logistics. Another variable concerns
who pays for the strategy. Strategies that provide quantifiable emissions benefits, such as
retrofit and idle reduction strategies, are often eligible for government funding, while owners
or operators typically pay for other strategies.
Cost can be a significant factor for drayage trucks crossing the border. Reducing emissions
from drayage operations has been called “one of the most challenging issues involving goods
movement” in part because drayage operations are typically low-margin businesses with few
capital resources. 29 Unlike other nonattainment areas in Texas, El Paso is not eligible for the
state’s Texas Emissions Reduction Plan (TERP) funds that can assist with the purchase of
diesel retrofits and other emissions-reducing activities. However, grant programs, such as the
Border 2012 program, could be a funding source for air pollution mitigation strategies.
Idle reduction technologies, improved freight logistics, and other fuel saving strategies will
typically pay for themselves with time. Often, uncontrolled idling is the most expensive option
29
California Air Resources Board. “Goods Movement Action Plan,” pg 93-4
http://www.arb.ca.gov/gmp/docs/gmap-1-11-07.pdf, accessed December 2008.
17
for a trucker. Fuel estimates for a 2001 truck idling uncontrolled are between 0.77 (if heating)
and 0.98 (if cooling) gallons per hour. For a 2008 truck, idling estimates are between 0.53 (if
heating) and 0.72 (if cooling) gallons per hour. 30 Payback estimates for idle reduction devices
typically range from two to three years depending on the extent of idling and the cost of diesel
fuel.
However, idle reduction technologies such as APUs require an upfront capital investment. This
study found that APUs (including installation) cost about $10,000-to-$12,000 per drayage
truck. This upfront price can be a barrier for drayage fleets. In addition, the payback period is
longer for drayage fleets than for many long-haul fleets because drayage trucks do not idle
overnight.
Emissions Reduced
Some strategies will reduce only a few pollutants, while others will reduce all emissions
collectively through decreased use. For example, DOCs and DPFs will dramatically reduce
PM, HCs, and CO, but will have no effect on NOx emissions. In contrast, engine, truck, and
tire modifications will reduce all emissions, if only marginally for some strategies.
Tradeoffs between emissions reductions and costs are common. For example, truck
replacement and repowers can dramatically reduce emissions but are also among the most
expensive options. Low viscosity lubricants are cheap but may have only a marginal effect on
emissions. Idle reduction technologies are an exception in that they can effectively reduce
emissions at a reasonable cost that can be recouped through fuel savings. However, there is no
idle reduction technology to address “creep” idling, which is common for drayage trucks
passing through the border ports of entry.
For nonattainment areas such as El Paso, the ability to quantify and verify the emissions
reduced for air quality plans is an important consideration. For a strategy to be included in a
State Implementation Plan (SIP), the emission reduction activities must be quantifiable and
verifiable. Diesel retrofits are frequently used in SIPs because the emissions reductions can be
easily and reliably estimated and applied. EPA and CARB’s technology verification programs
assign emissions reductions to verified technologies that can be used to calculate emissions
credit for SIPs. However, other strategies, such as auto tire inflation, low viscosity lubricants,
driver training, and improved freight logistics are difficult to quantify or have unknown
emissions benefits and therefore have not been commonly used in air quality plans.
As mentioned before, El Paso is in nonattainment for PM-10 and therefore would benefit from
technologies that reduce PM and can be incorporated into the SIP. These strategies would
include DOCs, DPFs, cleaner fuels, engine replacement, and truck replacement (including
replacement with SmartWay certified tractor/trailers and/or hybrid power-train technology).
Fuel Consumption
Strategies that reduce fuel consumption without negatively impacting operations are more
favorable to truck owner and operators. Fuel consumption, emissions reductions and costs are
30
Argonne National Laboratory. Handout: Which Idling Reduction Technologies are the Best? August 2008.
Available at: http://www.transportation.anl.gov/engines/idling.html.
18
closely related in that most fuel saving strategies reduce emissions and pay for themselves
through reduced fuel costs. Active DPFs are the only SmartWay strategy that can be expected
to have a slightly negative impact on fuel consumption because some active particulate filters
use small amounts of fuel to provide additional heat to oxidize the trapped PM. Other retrofit
strategies are expected to have negligible impacts of fuel economy, if any. Truck operations
and use will significantly affect a strategy’s fuel savings, which will be discussed in the next
section.
Applicability to Drayage Border Operations
Drayage and border operation discussed previously in the background information section of
this report lays the framework for assessing whether a strategy is applicable to drayage fleets
operating at the border. Truck operation can significantly affect the utility of various emissions
control and fuel-saving strategies. Aerodynamic devices and highway speed reductions provide
the most benefit to long-haul driving cycles and could be expected to provide only marginal
benefits to drayage trucks that operate at more variable and lower speeds. Since TTI’s prior
study found that idling at the border occurs at various locations and occurs in queues rather
than rest stations, electrified parking spaces would not be appropriate for the El Paso border
crossing. Passive DPFs require high operating temperatures that may not be sustained through
a drayage truck’s drive cycle, although data logging could confirm whether a truck’s typical
operation make it a candidate for a passive DPF system. DPF systems also require ULSD fuel,
which is available in the Mexican border cities of Ciudad Juarez, Ensenada, Mexicali and
Rosarito since January of 2007. Supply of ultra low sulfur diesel was to be introduced
nationwide in Mexico in September 2009. 31
Climate considerations also affect the utility of a strategy. Bunker heaters do not cool cabins,
which is an important factor in the hot southern climates along the border. Low viscosity
lubricants are also more effective in colder climates and automatic shut-down and start up
devices are more effective in mild climates that do not see temperature highs found at the
border.
While cleaner fuels, such as CNG and biodiesel, may be a viable option in the future, they are
currently not readily available at the El Paso border area. A new CNG station is expected in the
coming years, although there is currently no station available. The current supply of B20 is
limited to a local supply of 500,000 gallons per year and is located 20 miles north of the
border. Biodiesel is suspected to slightly increase NOx from diesel engines and thus is
considered inappropriate for ozone non-attainment areas.
The high age of many drayage trucks also eliminates some SmartWay strategies from being
applicable to drayage fleets. The research team talked to vendors of auto tire inflation systems
and found that only some axles and wheel configurations are appropriate for this strategy.
These systems are expected to acquire a mere 0.6 percent improvement in fuel savings for
long-haul operations and such a small difference may not appear in the project’s test results. 32
31
PEMEX, Investors Relations. http://www.ri.pemex.com/index.cfm?action=content&sectionID=23#Pregunta9.
Access in 10/20/2009.
32
Ang-Olson, J., and W. Schroeer. Energy Efficiency Strategies for Freight Trucking: Potential Impact on Fuel
Use and Greenhouse Gas Emissions. Transportation Research Record, No. 02-3877, 2002. p.13.
19
Similarly, it was found that single-wide tires can only be installed on newer rims, which
became popular starting in 1999. An evaluation of two of the largest drayage operators in the
El Paso- Cuidad Juárez area found that the vast majority believed that retrofitting their fleet
with single-wide tires would not be cost effective.
Maintenance
Strategies that require less maintenance or have maintenance benefits will be more acceptable
to owner/operators than those requiring significant upkeep and care. For example, SCRs
require periodic refilling of a reactant that necessitates a sufficient supply and monitoring for
low levels. Conversely, several strategies have maintenance benefits such as automatic tire
inflation, automatic shut down and start up devices, engine replacements, and truck
replacements.
Driver Comfort
Drivers often idle rather than shutting off their engines to maintain a comfortable cab
environment. While many of the strategies on the list are neutral to driver comfort, APUs and
electrified parking spaces provide air conditioning and electricity to the cabin while in use.
However, driver comfort was not found to be a top priority among the drayage truck drivers in
this project. Even if a drayage truck had a functioning air conditioning system, many drivers
did not turn on the systems.
ASSESSMENT OF SMARTWAY STRATEGIES
More than 20 SmartWay strategies were evaluated according to the criteria selection discussed
previously. Table 5 provides a summary of the SmartWay strategies and their fit for drayage
operations at the El Paso –Ciudad Juárez border. A plus sign (“+”) indicates an advantage and
a minus sign (“-”) indicates a disadvantage. A blank indicates either neutrality or that not
enough information about the strategy and how it applies to drayage trucks is known. Since
every strategy reduces emissions, only those that significantly reduce emissions and are easily
quantifiable and verifiable for SIPs are given a plus sign. Costs are given a plus sign if they
pay for themselves within a short timeframe (two-to-five years) or are relatively inexpensive (<
$1,000 per truck). Applicability was judged on whether the strategy would be effective in
drayage border operations along the southern border and not whether the strategy was
applicable to all drayage operations nationwide.
Some common strategies for reducing emissions were eliminated for consideration. Alternative
fuels, such as propane, are a SmartWay strategy but would require significant vehicle
conversions or be would be covered under a truck replacement strategy. Closed crankcase
ventilation and exhaust gas recirculation are omitted because these systems are not verified by
EPA or CARB by themselves and are instead coupled with other diesel retrofit technologies
that are included in the strategies considered. The strategies listed also do not include the
SmartWay operational strategies recommended for drayage trucks serving ports, such as the
EModal port community system, gate accessibility, and terminal appointment system. While
some of these systems may be modified for border use, the multi-jurisdictional players
involved in border operations could affect their application and would require more
examination and study.
20
Table 5. Summary of Benefits and Disadvantages of SmartWay Strategies
Applied to Drayage at the El-Paso-Cuidad Juárez Border Crossing.
Strategy
Auto-tire inflation
Low-rolling
resistance tires
Aerodynamic
improvements
Low-viscosity
lubricants
Lighter tractors and
trailers/
SmartWay certified
trailers
Cost
+
+
+
+
+
+
+
+
+
+
Automatic shut
down and start up
systems
Electrified parking
spaces
Hybrid power-train
technology
DPFs
SCRs
Engine replacement
Truck replacement
CNG
Biodiesel
Maintenance
_
Driver
Comfort
+
_
_
_
+
+
_
+
_
+
_
+
+
+
+
+
+
+
+
DOCs
DOC + Closed
Crankcase Filtration
Applicability to
Drayage Border
Operations
+
Bunker heaters
APUs
Emissions
(sizeable
and SIP
credible)*
Fuel
Use
_
_
+
+
+
+
+
+
+
+
_
_
+
_
_
_
_
_
_
+
_
+
+
+
+
+
+
+
_
+
_
+
Speed reduction
+
+
Driver Behavior
+
+
Improved freight
+
+
logistics
* Assumes that local mandates and funding sources do not affect SIP eligibility.
21
STRATEGY SELECTION FOR BORDER DRAYAGE OPERATIONS
Meetings were held with major drayage companies in the El Paso – Ciudad Juárez area to
discuss the various options and to obtain their input on what might work best for their
applications. Three strategies were selected for emissions testing on drayage trucks crossing
the El Paso – Ciudad Juárez border. Technologies for testing were selected from the previous
summary table by eliminating from consideration any technology with a significant drawback,
indicating a “-” sign. Also eliminated from consideration are technologies that could not be
tested in a reasonable time frame, such as improved freight logistics. While logistics strategies
are promising for the drayage sector, testing them would involve analysis, time, and resources
outside the scope of this project. Similarly, auxiliary power units are potentially a good
strategy, but will be tested under another TTI project. Based on the analysis, the following
technologies are selected for testing:
• DOCs;
• lighter tractors and trailers; and
• driver behavior (a.k.a. eco-driving)
DOCs are an established retrofit technology for the highway sector. In many cases, DOCs
replace the muffler and require no maintenance in most applications. The devices work best
with ULSD fuel, but can also tolerate the higher sulfur levels of Mexican fuel. EPA and
CARB’s technology verification programs have several DOCs that are verified for heavy-duty
on-road trucks. 33, 34
Lighter trailers are another option for drayage companies. For long-haul trucks, reducing 3,000
pounds by using lighter-weight components could save up to 500 gallons of fuel annually and
eliminate up to five metric tons of CO2. 35 This project examines whether a similar emissions
benefit would apply to the short haul characteristics of drayage fleets.
Emissions and fuel benefits from lighter tractors and/or trailers are often calculated differently
depending on whether truck loads are typically at the legal weight limit. Trucks are typically
either maxed out on volume (“cubed out”) or maxed out on weight (“grossed out”). For trucks
at the maximum weight limit, a lighter trailer allows more products to be transported, which
can help eliminate truck trips. The fuel and emissions benefit would be calculated on avoided
trips. For trucks that are cubed out and utilize the maximum volume available, the lighter
trailer would reduce the weight transported and the fuel and emissions benefit would be based
on difference in emissions between the normal heavier tractor and/or trailer and the lighter
tractor and/or trailer. The research team collected weight data on trucks crossing the border to
determine the typical drayage trailer loads and found that most drayage trucks were neither
cubed out nor grossed out. Therefore, any emissions reductions from lighter tractors can be
33
U.S. EPA. “Diesel Retrofit Technology Verification: Verified Technology List”,
http://www.epa.gov/otaq/retrofit/verif-list.htm, accessed March 2009.
34
CARB. “Verfication Procedure: Currently Verified”, http://www.arb.ca.gov/diesel/verdev/vt/cvt.htm, accessed
March 2009.
35
U.S. Environmental Protection Agency, SmartWay Transport Partnership. Weight Reduction,
http://www.epa.gov/smartway/transport/documents/tech/weightreduction.pdf, accessed November 2008.
22
calculated from the difference between emissions measured from a standard trailer and a
lighter trailer.
Driver behavior can also impact emissions and fuel consumption by using the vehicle more
efficiently. Driver education aimed at reducing aggressive driving with frequent and rapid
stops and starts have been shown to positively impact fuel economy and emissions for urban
bus drivers and passenger vehicle drivers in Europe. 36, 37 One U.S. study estimated that driver
education can result in a 5-10 percent fuel economy gain for long-haul trucking. 38 While
promising, the research team did not locate any studies that examined the driving behavior of
drayage operators or utilized in-use emissions measurement. While driving behavior can refer
to a host of driving and maintenance practices, this study specifically examined the fuel and
emissions impact of rapid starts and stops, which are often termed “jack rabbit driving.” For
passenger vehicle drivers, it is estimated that gentle accelerations and braking can save more
than $1 per gallon. 39 While this estimate cannot be directly compared to heavy-duty diesel
vehicles, rapid starts can be expected to produce a disproportionate amount of emissions and
fuel use similar to any high-powered event.
36
Zarkadoula, M., G. Zoidis, and E. Tritopoulou. Training Urban Bus Drivers to Promote Smart Driving: A Note
on a Greek Eco-Driving Pilot Program. Transportation Research Part D 12 (2007) 449-451.
37
Beusen, B. and T. Denys, “Long-Term Effect of Eco-Driving Education on Fuel Consumption Using an OnBoard Logging Device.” In Urban Transport, XIV 295, 2008.
38
Ang-Olson, J., and W. Schroeer. Energy Efficiency Strategies for Freight Trucking: Potential Impact on Fuel
Use and Greenhouse Gas Emissions. Transportation Research Record, No. 02-3877, 2002. p.13.
39
EcoDriving USA. Eco-Driving Practices, http://www.ecodrivingusa.com/#/ecodriving-practices/, accessed
August, 2009.
23
4. IN-USE TESTING: PREPARATION AND PROCEDURES
Successful in-use emissions testing is the result of good preparation and procedures. In this
section, the procedures and approach taken to prepare and conduct the in-use testing are
described.
PREPARATION FOR IN-USE TESTING
There are several preparatory steps necessary for conducting in-use emissions testing. A testing
location and approved traffic management plan must be secured. SmartWay strategies have to
be specifically defined and procured, and drayage vehicles and drivers must be selected. For
this study, duty cycles also had to be developed from GPS data.
Testing Location and Traffic Management Plan
The research team selected a testing location that would allow for the safe operation of
vehicles with minimal disruption to normal transportation operation. Since the study was
replicating drive cycles that included idling at border POEs, the location had to allow for the
idling and slow movement of vehicles as well as high speeds to simulate highway conditions.
The road section on US 54 from McCombs Street to the border with New Mexico was found to
have conditions that allow a safe maneuvering of vehicles during the emissions testing and
represented a low hazard to local drivers. The area around the road has a low population
density and there is minimal development in the surrounding area.
The testing location consisted of 6.27 miles of double-lane road with right and left shoulders 6
feet wide and four major U-turns 100 feet wide each. The stretch has no major driveways or
connection to residential or commercial zones, and very little traffic. Figure 3 shows a map of
the roadway with the roadway appearing as the blue line.
Figure 3. Site Location of Road Testing, US 54.
The Texas Department of Transportation (TxDOT) requires an approved traffic management
plan for use of the roadway. The study team worked with TxDOT to create a plan following
the agency’s Traffic Control Plan Standards and the Texas Manual of Uniform Traffic Control
24
Devices. This included ensuring that proper signs were posted (Figure 4) and that the
appropriate trail and shadow vehicles were used during use of the roadway.
Figure 4. Photograph of Two Truck-Mounted Attenuators following a Drayage Truck
during Testing to Warn Drivers of Atypical Conditions.
In-use testing also requires space for equipment installation on vehicles and storage of testing
equipment, supplies, and vehicles. TxDOT generously donated space for testing at one of their
district offices located close to the roadway used for testing. The convenient location also
included gate controlled access that provided the necessary security for storing test vehicles
and testing equipment.
SmartWay Strategies
The three SmartWay strategies selected for testing are DOCs, lighter trailers, and driver
behavior. Each strategy required a unique process or procedure for effective emissions
measurement.
DOCs
The EPA and CARB both have a retrofit verification program that lists DOCs that have been
evaluated for emissions performance. The verified technology lists specify expected emissions
reductions for specific applications. 40 For this study, only EPA- or CARB-verified products
40
EPA verification list, http://www.epa.gov/otaq/retrofit/verif-list.htm and CARB verification list,
http://www.arb.ca.gov/diesel/verdev/verdev.htm.
25
were considered. Based on price, availability, and time of delivery, the AZ Purimuffler and AZ
Purifier systems manufactured by Engine Control Systems were selected for this project.
Depending on the vehicle retrofitted, the systems are expected to reduce PM by 20-40 percent,
CO by 40 percent, and HC by 50-70 percent. The systems require little, if any, maintenance.
DOCs replace a vehicle’s muffler and are composed of a honeycomb-like structure coated with
a catalyst that breaks down exhaust components into less harmful substances. The systems
have to be sized correctly to fit the vehicles, but installation typically only took about three
hours. There was no DOC installation or usage issues associated with this project.
Lighter Trailers
Lighter trailers translate into less work for the tractor engine and therefore reduced emissions.
Some trailer manufacturers such as Great Dane, Utility, Wabash, Vanguard, New Life
(formerly Trailmobile), and others have reduced the weight of some trailers through advanced
designs and lighter materials. To determine the difference between a standard trailer and a
lightweight model, the research team examined the weight specifications for new 53-foot
trailers and the lower-weight models. The weight of a typical trailer averaged about 14,000
lbs., while the ultra-lightweight trailers weigh about 12,000 lbs. This 2,000 lb. difference may
be a conservative estimate considering that most drayage fleets are using old trailers that are
heavier than the new, standard trailers. The use of a lighter trailer was simulated during testing
by removing 2,000 lbs. of load.
Driver Behavior
There are many aspects of driving behavior that could be tested, such as good maintenance
practices and following the speed limit. The few academic studies performed on eco-driving
have examined the impacts of driver education programs. This approach required more time
than available and would not have indicated which aspects of driver behavior have a significant
impact on emissions and fuel consumption. This project took a very specific approach that
focused only the impact of rapid accelerations. Unlike long-haul trucking, drayage-operating
cycles include a lot of starting and stopping, both at border crossings and through city traffic in
between destinations. Accelerations are high emissions events with concentrated emissions in a
short time span. Drayage vehicles may often be operating their engines at maximum loads to
achieve rapid accelerations. Of the many eco-driving tools, it could be concluded that reducing
rapid accelerations may be among the most promising tools for reducing drayage emissions.
To evaluate the impact of rapid accelerations, data was collected at baseline conditions where
drayage drivers were told to operate the vehicles normally and then during test runs where
drivers were told to deliberately accelerate at a relaxed pace.
Selection of Drayage Trucks
Five drayage vehicles were selected from two of the largest drayage fleets operating in El
Paso- Cuidad Juárez. Vehicles were selected based on the prevalence of make and model year
as well as diversity of engine make and model. The selection of model years also spans several
emissions standards established in 1988, 1990, 1991, 1994, 1998, and 2003. The selected
sample covers almost 75 percent of the drayage fleet in terms of emissions standard
classification with only the newest model years and MY 1990-1993 are not represented (the
26
latter category is only slightly different from post 1994 category). The 1998 International
represented the most prevalent make and model and the Freightliner represented the second
most popular model with 1999 being the most common model year for that vehicle make from
one of the companies. A 1986 International truck was the most prevalent vehicle type from the
other company, with the next two vehicles selected representing the next most common vehicle
models and model years within the fleet (Table 6).
Table 6. Drayage Trucks Selected for Testing.
Model
International
White GMC
Volvo
International
Freightliner
Model
Year
1986
1994
1996
1996
1999
Engine
Manufacturer
Cummins
Detroit
Cummins
Detroit
Cummins
Engine
Model
Big Cam
S-60
M11
S-60
ISM
Engine HP
300
360
330
330
330
Test Drive Cycles
This study used a series of flexible driving cycles for collecting in-use data. Because the term
“driving cycle” is usually used for fixed and inflexible speed profiles that the test vehicles must
follow, the flexible drive cycles used in this study are referred to as “drive patterns” to
distinguish this difference. The drive patterns used in this study consist of a series of driving
guidelines and simple speed profiles to be loosely followed which cover a wide variety of a
vehicle’s operation i.e. different combinations of instantaneous speeds and acceleration rates.
All test runs for each drayage vehicle followed the same established driving pattern. Using a
drive pattern rather than just collecting data on a normal workday has three main advantages.
First, the use of driving patterns enables tests to be comparable with each other, so that
baseline tests can be more accurately compared to tests incorporating a SmartWay strategy.
Drive patterns also allow tests to be repeated, which improves the quality of the data. For this
project, each drayage truck repeated the normal driving pattern a minimum of five times.
Finally, drive patterns can also incorporate all operation modes, even the high-emissions events
that may occur on an atypical basis. If data was collected during a normal workday, then data
reflecting high engine loads may not be adequately collected. For this study, a typical drive
pattern was augmented with an uphill portion where the vehicle was forced to work at
maximum load.
Figure 5 depicts the speed profile and driving events used for this project. The creep idle event
was specifically included to reflect the emissions impacts of border crossings at U.S./Mexico
POEs. Drayage vehicles repeated each event, except for the uphill portion, for a minimum of
five repetitions. Depending on the running conditions of test vehicle, one-to-three runs of
uphill data was collected. A period of at least 20 seconds of stop time was included in between
27
each run to let the engine stabilize to unloaded conditions and therefore minimize any possible
effects of the previous run. A normal deceleration was considered for all events, except for the
driver behavior testing that required gentle accelerations.
Figure 5. Driving Event Speed Profiles used in the Study.
80
Downhill
Speed (mph)
Uphill
Step High
High Acc.
Acc.
Low
Acc.
Step Normal
60
40
Creep Idle
20
0
0
100
200
300
400
500
600
700
800
900
1000
Time (s)
IN-USE TESTING
In-use testing involves a series of steps including PEMS installation, equipment calibration,
data collection and monitoring and uninstallation. This section describes the in-use testing
process conducted for this project and any anomalies that occurred in collecting the data. Since
in-use testing is conducted in the field, it is subject to unforeseen and random events that can
occur in normal drayage operations. There were few unexpected events for this study, with a
one notable exception that is discussed in this section.
Testing Equipment
This study used two PEMS units simultaneously to collect in-use emissions data. The
SEMTECH-DS system was used to collect gaseous emissions NOx, HC, CO, and CO2, and
TTI’s Axion system manufactured by Clean Air Technologies International, Inc. was used to
measure PM. The units are pictured in Figures 6 and 7, respectively. The following sections
describe the two units.
SEMTECH-DS
The SEMTECH-DS system is manufactured by Sensors Inc. and includes a set of gas
analyzers, an engine diagnostic scanner, a GPS, an exhaust flow meter (EFM) and embedded
software. The gas analyzers measure the concentrations of NOx (NO and NO2), HC, CO, CO2,
and oxygen (O2) in the vehicle exhaust. The SEMTECH-DS uses the Garmin International,
Inc. GPS receiver model GPS 16 HVS to track the route, elevation, and ground speed of the
vehicle on a second-by-second basis. TTI’s SEMTECH-DS uses the SEMTECH EFM to
measure the vehicle exhaust flow. Its post-processor application software uses this exhaust
28
mass flow information to calculate exhaust mass emissions for all measured exhaust gases. The
unit meets all of EPA’s in-use compliance equipment specifications.
Figure 6. TTI’s SEMTECH-DS Unit.
Axion System
The Axion system is comprised of a gas analyzer, a PM measurement system, an engine
diagnostic scanner, a GPS, and an on-board computer. For this study only the PM
measurement system was used. The PM measurement capability includes a laser light
scattering detector and a sample conditioning system. The PM concentrations are converted to
PM mass emissions using concentration rates produced by the Clean Air Technologies Inc. unit
and the exhaust flow rates produced by the SEMETCH-DS unit.
Figure 7. TTI’s Axion Unit.
29
Testing Procedures
The EPA has an in-use testing program for demonstrating compliance with heavy-duty diesel
emissions standards. 41 This program governs the standards for PEMS equipment and was
followed for this project. Under this rule, the EPA’s engine-testing procedures, 40 CFR Part
1065, describes PEMS testing procedure for gaseous sampling including NOx, CO, HC, CO2
in a high level of detail, and specifies the instruments required for these tests. For example, a
flame ionization detector (FID) must be used to measure HC emissions. EPA currently does
not accept in-use testing data for PM for compliance purposes. However, the procedures used
in this study for PM testing are largely the same as for other pollutants. For example, flow
meter specifications met the provisions that should be used to measure exhaust flow. TTI’s
equipment complies with all the specifications of the EPA rules, and the research team
followed the applicable testing procedures outlined in EPA’s rules for this project. In general,
the testing procedures include proper equipment installation, calibration, and verification, as
well as calculation procedures. Pictures of equipment installation are shown in Figure 8.
Each drayage truck repeated the same drive cycle a minimum of five repetitions for each test.
The trailer was loaded with the PEMS units and cement pallets to equal the typical drayage
load. Weight data collected at the border crossing showed that drayage trucks are loaded with
an average of 20,000 lbs. of cargo (Figure 9). Both of TTI’s PEMS units were installed in
front of the trailer as shown in Figure 9. The last pallets equaling 2,000 lbs. were removable
with a forklift, which was removed to simulate a lighter trailer. A baseline test for each truck
was followed by tests for lighter trailers and slower accelerations. DOCs were installed and
then the truck was returned to the drayage fleet for a degreening period. The degreening
process allows catalysts to stabilize. EPA recommends a minimum of 25 hours for DOCs. This
project exceeded the minimum degreening thresholds by returning the drayage vehicles back to
regular service for two or three weeks before performing the DOC in-use tests.
Since testing is conducted in the field under minimally controlled conditions, unexpected
events can occur even with the best preparation, equipment and plans. For this project, one
drayage truck suffered an engine failure and could not be tested with the DOC installed. This
resulted in a loss of data for one test involving a DOC. However, test data on lighter trailers
and driver behavior was collected on the vehicle before the vehicle breakdown.
41
U.S. EPA. In-Use Testing Program for Heavy-Duty Diesel Engines and Vehicles. EPA420-F-05-021, June
2005, http://www.epa.gov/oms/regs/hd-hwy/inuse/420f05021.pdf, accessed August, 2009.
30
Figure 8. Photographs of Pre- and Post DOC installation (Left Photo Shows the Exhaust Flow
Meter (EFM) Being Installed for the Baseline Test; Right Photo Shows the Same Vehicle with the
DOC Installed.
Figure 9. Photograph of Inside Testing Trailer with TTI’s PEMS Units installed in the
Front of the Trailer and Concrete Pallets Used to Simulate a Typical Load (The last pallet
was removable to simulate a lighter trailer).
31
5. RESULTS
The data recorded by the two PEMS units were in second-by-second format. From the entire
array of information that was recorded (emissions, ambient conditions, and vehicle parameters)
the following information was extracted and used in this study:
•
engine parameters (if recorded) such as engine speed, throttle position, and engine load
for data quality checking;
•
second-by-second vehicle speed from the GPS in mph; and
•
emissions mass rates in grams per second (g/s).
Second-by-second emissions data were carefully aligned with the instantaneous speeds
obtained from the GPS data. A linear smoothing was applied to speed and grade data to cancel
out noise and fine-scale changes due to GPS accuracy limitations and other factors. The VSP
value corresponding to each instance was calculated based on equation 1. Table 7 lists the
values of parameters A, B, and C used for VSP calculation. These values were obtained from
the MOVES source database.
Table 7: MOVES’ Vehicle Parameters Values.
Combination
Short-Haul Truck
* Light trailer results.
Rolling Term A
Rotating Term B
Drag Term C
Vehicle Mass (tonne)
1.96354
0
.00403054
29.3275 (28.4203*)
The second-by-second emissions rates were then grouped into operating mode bins according
to Table 4. Modal average emissions rates for all the pollutants were then estimated for each
bin using all the observations that fall into that modal bin. Chauvenet's criterion was applied to
emissions rates of each bin to identify and filter out the outliers. 42 Not all the bins had enough
data to determine their corresponding emissions rates. This is usually the case for high VSP
bins, which barely occur during the normal operation of drayage trucks. For these bins, it was
assumed that their emissions rates are equal to the bins that have immediate lower VSP limits
in the same speed category. For example, if emissions rates were missing for bin 16, emissions
rates of bin 15 were used instead. It is determined that the errors introduced by applying this
assumption is minimal because the number of high VSP bins are very small compared to lower
VSP bins that data were available for them.
MODAL EMISSIONS
Figures 10 and 11 show the average base case emissions rated of all operating modes for the
oldest (1986 International Truck) and newest (1996 Freightliner Truck) tested vehicles. As
mentioned previously, due to an engine failure, no data was collected for the 1996 Volvo with
the DOC installed. As Figure 10 shows, there was not any data for higher VSP bins, which
corresponds to high engine load, and therefore they are assumed to be equal to their previous
42
Taylor, J.R. An Introduction to Error Analysis. 2nd edition. University Science Books, Sausalito, CA, 1997.
32
bins. The results for the other vehicles were qualitatively similar and therefore are not
presented here.
Figure 10. Average Modal Emission Rates for the 1986 International Truck.
0.50
30
0.45
25
0.40
0.35
NOx (g/s)
CO2 (g/s)
20
15
10
0.30
0.25
0.20
0.15
0.10
5
0.05
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0.00
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0
VSP Bin
VSP Bin
3
0.045
0.040
2.5
0.035
0.030
THC (g/s)
CO (g/s)
2
1.5
0.025
0.020
0.015
1
0.010
0.5
0.005
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0.000
0
VSP Bin
VSP Bin
0.045
0.040
0.035
PM (g/s)
0.030
0.025
0.020
0.015
0.010
0.005
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0.000
VSP Bin
The emissions rates shown in Figure 11 indicate that the modal emissions rates of newer
drayage trucks, which are in good running conditions, such as the 1999 Freightliner truck,
generally increase as the VSP value increases. The exception to this trend is CO at speed
between 25-to-50 mph, which has higher emissions rates for bins with medium VSP values
than bins with higher VSP values. This could result from fewer observations being collected
for these bins compared to lower VSP bins; however, the impact of this issue is minimal
because very few instances of these high VSP bins occur during normal drayage operations.
33
Figure 11. Average Modal Emission Rates for the 1999 Freightliner Truck.
30
0.40
0.35
25
0.30
NOx (g/s)
CO2 (g/s)
20
15
10
0.25
0.20
0.15
0.10
5
0.05
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0.00
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0
VSP Bin
VSP Bin
0.25
0.008
0.007
0.20
THC (g/s)
CO (g/s)
0.006
0.15
0.10
0.005
0.004
0.003
0.002
0.05
0.001
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0.000
0.00
VSP Bin
VSP Bin
0.012
0.010
PM (g/s)
0.008
0.006
0.004
0.002
0
1
11
12
13
14
15
16
21
22
23
24
25
27
28
29
30
33
35
37
38
39
40
0.000
VSP Bin
For the older vehicles, which are at poorer running conditions, such as 1986 International in
Figure 10, the results show that THC emissions are higher in low VSP bins. This trend is a
strong indication of incomplete combustion. This is also true to some extent for CO emissions
as shown in Figure 10.
CO2 and NOx show a consistent trend; higher VSP bins have higher emissions rates. CO2
formation is the direct result of combustion and therefore a strong indicator of fuel
consumption. Combustion temperature is the main factor determining the NOx formation rate.
Higher engine load is equal to higher temperatures, and therefore more NOx is formed. Note
that high load conditions are very small fractions of normal drayage driving patterns, and the
vast majority of normal driving is under low and medium engine loads.
To validate the modal emissions rates, these average rates were applied to each corresponding
instant of the observed data and the total emissions were calculated for highway section of
testing. The highway section used in this validation effort includes various activities including
34
low and high acceleration, cruise driving, and creep idling. The results of this validation effort
are demonstrated in Appendix A. The values in this table are the percentage difference
between the estimated values and observed emissions.
The results of this validation effort show that in general the average modal rates provide
satisfactory results for no-grade and uphill driving for all pollutants. The PM emissions of
creep idling are generally overestimated, while the estimates for other emissions are near the
observed values. This is because creep idle is a low-speed and low-power event and the mode
bins describing it (bin 12 and 13) cover a wide speed range (0-25 mph), and therefore tends to
overestimate PM emissions. Downhill has the lowest overall accuracy. This is because the
engine is not working under constant load and load variability is higher than for the other
modes. CO2 rates provide the most accurate estimates for all modes while other pollutants
show mixed results. Overall, it appears that the average modal emissions rates provide
relatively accurate estimates for the majority of driving events; i.e. driving on zero-to-moderate
grade roads. A sample of the operating modes results is provided in Table 8. The rest of the
results are qualitatively the same and they are not included in the report.
Table 8: Deviation of Estimated Modal Emissions from the Observation for the 1986
International Truck With Degreened DOC.
Deviation from Observation (%)
CO2
CO
NOx
THC
PM
Uphill
-6.1% 175.5% -21.4% 1555.9% 12.9%
Downhill
133.6% 61.4% 160.1%
-4.0%
83.2%
Flat Road (highway 54)
1.0%
4.1%
-2.4%
-1.7%
0.3%
IMPACT ANALYSIS
The main question for this study is whether the selected SmartWay strategies are effective in
reducing emissions from drayage fleets operating at the U.S./Mexico border. For this purpose,
the modal emissions rates for each vehicle were applied to a series of drive cycles that were
collected using GPS. These emissions estimates were then used to investigate the impact of the
selected strategies. To collect speed data for drive cycles, GPS units were installed on three
different vehicles in Laredo, TX and second-by-second speed data were collected for an entire
day of drayage operation including driving in the U.S. and Mexico, as well as north- and southbound border crossings. A total of 35 drive cycles were examined in this effort. Figure 12
shows a sample of these analysis drive cycles.
The average total emissions for each scenario were calculated for each cycle. These estimates
were then used to calculate the average impact of each strategy. All the statistical analyses
were performed at 95 percent confidence level. Two scenarios were investigated for the ecodriving strategy. It was assumed that drivers will use lower acceleration rates, and therefore
partial acceleration rates, 80 percent and 50 percent of the observed rates, were used for this
purpose. New drive cycle operational mode distributions were calculated and total emissions
were estimated based on these updated distributions and the base case emissions rates. It was
determined that a 50 percent change in acceleration requires changing the drive cycles
35
significantly to accommodate for the dramatic distance and time differences, and therefore
results of the 50 percent acceleration scenario should be treated only as general indications of
the direction and amount of potential changes.
Figure 13 shows the results of this analysis in graphical form. These results are also presented
in tabular format in Appendix A. The CO2 results, which are a direct indicator of fuel
consumption, show that the light trailer and eco-driving at 80 percent acceleration scenarios
have no apparent impact on CO2 emissions and fuel consumption for the drayage trucks;
whereas, DOC causes a small increase in CO2 emissions. The 8.1 percent CO2 reduction from
the eco-driving at 50 percent acceleration scenario should be considered carefully since the
drive cycles were not updated to reflect the changes in duration and distance.
Figure 12. Example Analysis Drive Cycles.
35
20
North Bound Border Crossing
South Bound Border Crossing
15
Speed (mph)
Speed (mph)
30
10
25
20
15
10
5
5
0
0
0
500
1000
Time (s)
0
1500
60
500
1000
1500
Time (s)
2500
60
U.S. Driving
Mexico Driving
50
Speed (mph)
50
Speed (mph)
2000
40
30
20
10
40
30
20
10
0
0
0
500
Time (s)
1000
0
500
1000
1500
Time (s)
2000
As expected, the CO results show a major (78.2 percent) reduction as the result of using DOCs.
This is also true for the THC emissions with an average 52.6 percent reduction. Deploying
DOCs also resulted in an 8.4 percent reduction in PM emissions and a 5.3 percent increase in
NOx emissions. The DOCs used in this study were verified by the EPA to reduce PM by 20-40
percent, CO by 40 percent, and HC by 50-70 percent. While the retrofits in the study
performed as expected for CO and THC, the small reduction in PM does not correspond to the
technology’s EPA verification levels. This is because DOCs can potentially change the size
distribution of PM emissions, and light scattering techniques, such as the one used in this
study, usually cannot detect these changes. A gravimetric measurement (i.e., filter sampling
36
method) can more accurately show the changes regardless of changes in PM emissions size
distribution.
The results indicate that using a lighter trailer can provide CO, THC, and PM reduction
benefits, however it appears that it does not have a noticeable impact on NOx emissions for the
drayage fleet. A modest reduction of all criteria emissions (CO, NOx, THC, and PM) is
observed for the eco-driving at 80 percent acceleration scenario. PM and CO have the highest
reduction at 15.7 percent and 13.6 percent, respectively; while NOx has the lowest with a 2
percent reduction.
DOC
80% Eco
Driving
50% Eco
Driving
5.2
5.2
5.5
5.1
4.9
Base
Light
Trailer
DOC
80% Eco
Driving
50% Eco
Driving
0.57
0.53
0.27
0.53
0.57
2
80% Eco
Driving
50% Eco
Driving
427.1
428.1
435.7
426.8
392.7
0
NOx (kg)
10
0.6
0.5
THC (kg)
6
‐13.6 %
8
+ 1.3 %
0.7
4
0.4
0.3
0
‐ 52.6 %
‐78.2 %
0.2
2
0.1
Base
Light
Trailer
DOC
80% Eco
Driving
50% Eco
Driving
11.0
9.5
2.8
9.5
11.2
+ 0.4 %
DOC
‐7.9 %
Light
Trailer
‐8.0 %
Base
‐ 13.9 %
CO (kg)
Light
Trailer
3
12
CO (kg)
Base
4
1
0
CO2 (kg)
‐6.09 %
100
‐ 2.0 %
200
+ 5.3 %
NOx (kg)
300
+ 0.3 %
5
‐ 8.1 %
400
‐ 0.1 %
6
+ 2.0 %
500
+ 0.2 %
CO2 (kg)
Figure 13. Total Emissions Results from Analysis Drive Cycles.
0
THC (kg)
0.6
0.2
* an adjusted baseline value of 0.40 kg is used in this
calculation
‐1.8 %
‐15.7 %
0.3
‐8.4 % **
0.4
‐4.4 % *
PM (kg)
0.5
** an adjusted baseline value of 0.59 kg is used in this
calculation
0.1
0
PM (kg)
Base
Light
Trailer
DOC
80% Eco
Driving
50% Eco
Driving
0.53
0.38
0.53
0.44
0.52
These corrected baseline values reflect the lack of PM
data for one vehicle in a specific scenario
Eco-driving at 50 percent acceleration rates appears to have no or lower emissions reduction
benefits for CO, THC, and PM. This is because some of the modal bins with higher VSP
values have lower emissions rates and therefore lowering the needed power increases these
pollutants. As expected, lower acceleration and engine load in this scenario reduces NOx
emissions. This is because NOx is formed under high load and engine temperatures, and
therefore reducing these factors decreases the amount of NOx formed during combustion. It is
37
important to emphasize that the analysis drive cycles used in this analysis were not modified to
reflect the impact of utilizing a 50 percent acceleration rate. The analysis is an attempt to
investigate low-acceleration driving, and therefore the results should be interpreted as an
indication of direction of the changes and not the final reduction or increase values.
38
6. CONCLUDING REMARKS
This research examined the air quality and GHG emissions impacts of three different
SmartWay strategies for drayage fleets operating at the U.S./Mexico border. The following are
the main findings and implications of this research.
•
Drayage operations occurring along the southern border is an important source of
emissions.
•
This study evaluated the emissions and fuel impact of three promising SmartWay
strategies with potential benefits for border drayage operations. The three SmartWay
strategies were driver behavior (eco-driving), lighter trailers, and DOCs.
•
Strategies were selected based on multiple criteria including cost, emissions reduced,
and applicability to the short-haul operations used by drayage fleets. Five representative
drayage vehicles were selected for testing.
•
Installing single wide tires require newer rims than what are normally found on drayage
trucks. Installing compatible rims is not a cost effective option, therefore this strategy
was found to be ineffective for drayage fleets operating at the southern border. Auto air
inflation had a similar issue in that the strategy requires a certain type of axel to be used
cost effectively.
•
Data collection and data analysis methodologies were proposed to estimate the
emissions impact of drayage trucks and emissions reduction strategies. The proposed
methodology reduces the duration of data collection and enables researchers to
investigate broad operation modes.
•
The selected drayage trucks were tested for emissions and fuel economy before and
after the implementation of a SmartWay strategy. Second-by-second emissions of these
five drayage trucks were collected for three different cases; baseline, lightweight
trailers, and DOCs. The proposed methodologies are based on VSP factors as defined
for the EPA’s MOVES model.
•
Data were analyzed based on MOVES’ VSP-based approach. Eco-driving was
analyzed by modifying the acceleration rates of the speed profiles that were used in the
analysis. All the statistical analyses were performed at 95 percent confidence level.
•
The results show statistically significant CO and THC reductions as the result of
installing DOCs. Fuel consumption was found to be marginally affected by all the
tested strategies.
•
Using a lightweight trailer provided modest CO, THC, and PM reduction benefits, but
no statistically significant impact on NOx.
•
Eco-driving at an 80 percent acceleration rate provided statistically significant CO,
THC, and notable PM reduction benefits; however, eco-driving at a lower acceleration
rate (50 percent reduced acceleration rate) was not as effective. The results suggest that
NOx and fuel consumption reduction are the major benefits of eco-driving at low
acceleration rates.
39
Thus, the findings from this research provide the basis for assessing the air quality impacts of
drayage freight operations at the border region, refining and improving data collection and
analysis methodologies, and developing effective emissions reduction programs.
40
7. RECOMMENDATIONS
The research team recommends the following based on the results of the study:
•
The results indicate that eco-driving is a promising strategy for reducing drayage
emissions and fuel consumption cost effectively. The research team recommends
consideration of an Eco Driving pilot program targeting the drayage fleet at major ports
of entries in U.S.-Mexico border region.
•
DOCs were found to be effective in reducing CO, THC, and PM from drayage
operations. The research team recommends DOCs to be considered where PM, CO, and
HC emissions reductions are desired. DOCs are relatively inexpensive and are a cost
effective emissions option where funds and incentives are provided to drayage fleets.
•
It is highly recommended that improvements to drayage operation logistics be studied
and pursued. The load weight data collected at border crossings reveal that a significant
portion of the drayage capacity is underutilized. Higher utilization of the existing
capacity is anticipated to reduce the number of cross-border drayage trips and the
associated emissions and fuel consumption.
The study revealed areas where further research is needed. Future projects that could
effectively build off of the results of this study are below:
•
Eco-driving is fairly a new concept in heavy-duty diesel truck operation. Different
strategies such as progressive shifting and lower acceleration rates fall under ecodriving strategies. New research is needed to identify the most effective eco-driving
strategies suited for drayage operations and for determining the overall effectiveness of
the strategy and method of deployment.
•
The EPA verified PM emissions reduction levels for DOCs were much higher than the
results found in this study. Further research is needed to explain these results. While
this study primarily estimated PM number, the pollutant can also be measured by size
distribution and mass. One possible explanation for this study’s findings is that DOCs
in drayage fleets change the size distribution and/or mass of PM emissions. In order to
investigate the complete impact of DOCs on PM emissions, in-depth PM
characterization studies using particle size distribution and filter mass measurement
instruments are required.
•
The overall vehicle sample size of five is relatively small compared to the diversity of
the in-use fleet. Having a larger sample size would increase the statistical confidence
and applicability of the results. A sample that includes at least three vehicles per
emissions standard class would provide a better picture of the average emissions
characteristics of heavy-duty drayage trucks.
•
This study could be replicated for the northern U.S. border or for other types of fleets
and operations. Vehicle class and operating conditions vary widely among applications
and should be studied separately in order to develop applicable conclusions for those
classes.
41
8. ACKNOWLEDGEMENTS
This research effort was funded by the Texas Commission on Environmental Quality with
funding from the EPA, Region 6 through the U.S./Mexico Border Air Quality Program. The
authors would like to thank Ross Pumfrey and Ed Moderow of TCEQ and Eduardo Calvo of
TxDOT for their guidance and support during the project. The authors would like to thank
TxDOT’s El Paso District for use of their facilities during emissions testing.
The TTI research team would like to thank Mr. Manuel Sotelo with Fletes Sotelo and Mr.
Hector Mendoza with STIL for their collaboration during the in-use emissions testing of the
technologies for this research. Five Drayage trucks from these two drayage trucking
companies were provided for the study, allowing the research team to perform tests with a
“real-life” sample of drayage vehicles in the region.
The authors would also like to thank the following TTI researchers for their contributions
without which this study would not have been possible – Juan Villa, Rafael Aldrete, Edward
Brackin, Melisa Finley, Noel Chavez, Luis David Galicia and Osiris Vidana. Finally, the team
appreciates the insight and essential input from Cheryl Bynum from the EPA SmartWay
Transport Program for her assistance in the selection of SmartWay strategies for emissions
testing.
42
APPENDIX A
Table A.1. Validation Results: Total Emissions Change from Observation.
Base
Vehicle 1 Light Trailer
DOC
Base
DOC
Base
DOC
Base
DOC
Base
DOC
CO2
10.5%
0.4%
0.2%
0.4%
3.1%
1.0%
-13.1%
0.0%
N/A
-0.3%
1.1%
1.1%
0.0%
-0.2%
0.8%
Change (%)
CO
NOx
THC
-2.1%
-3.4%
-1.1%
-2.4%
0.8%
-1.6%
-43.2% 0.2%
-3.9%
5.2%
0.0%
4.1%
3.0%
2.4%
7.9%
4.1%
-2.4%
-1.7%
0.1%
0.0%
23.1%
-4.2%
0.2%
-1.6%
N/A
N/A
N/A
-2.3%
3.9%
4.3%
5.8%
1.6%
1.7%
0.3%
3.0%
N/A
4.9%
5.4%
-0.8%
2.4%
7.5%
5.1%
2.6%
9.8%
-1.5%
PM
-1.3%
-2.1%
-2.4%
-5.5%
N/A
0.3%
N/A
N/A
N/A
5.3%
5.6%
1.3%
2.2%
1.0%
16.8%
Table A.2. Total Emissions Results from Analysis Drive Cycles.
* based on an adjusted baseline value of 0.40 kg
** based on an adjusted baseline value of 0.59 kg
These corrected baseline values reflect the lack of PM data for one vehicle in a specific scenario
43
APPENDIX B
Summary Fuel Consumption and Emissions Report
for
CARBON CHAIN TECHNOLOGIES LIMITED
Testing 2ct® Treated Gasoline and Diesel Fuels
Prepared by the
Texas Transportation Institute
March, 2009
TEXAS TRANSPORTATION INSTITUTE
The Texas A&M University System
College Station, Texas 77843-3135
44
SUMMARY
This report summarizes the results of collaborative testing performed by team members from
the Texas Transportation Institute, Clean Air Technologies Inc. and Sensors, Inc (the research
team) in 2008. The tests were performed at the Pecos Research and Testing Center (RTC)
outside Pecos, Texas. The research team used well-known industry standard test procedures,
details of which are fully documented together with the specific test procedures and conditions
in separate full reports published by TTI, entitled “Fuel Consumption and Emissions Report for
CARBON CHAIN TECHNOLOGIES LIMITED - Testing 2ct® Treated Gasoline Fuel” and
“Fuel Consumption and Emissions Report for CARBON CHAIN TECHNOLOGIES LIMITED
- Testing 2ct® Treated Diesel Fuel”.
In summary, the results presented in these reports demonstrate that gasoline and diesel fuels
that were treated with 2ct® combustion enhancer improved the fuel consumption of the tested
vehicles by 7.3% and by 13.7% respectively.
The results also show statistically significant changes of carbon dioxide (CO2) and gasoline
carbon monoxide (CO). For treated gasoline, CO2 was reduced by 6.9% and CO was reduced
by 27.1%. For treated diesel fuel, CO2 was reduced by 5.4% and CO increased by 6%
(although the latter was statistically insignificant).
INTRODUCTION
Recent increases in the cost of petroleum-based fuels have resulted in an unprecedented
interest in products that have the potential to improve fuel economy. At the request of Carbon
Chain Technologies Limited (CCT), the Texas Transportation Institute (TTI) in conjunction
with Sensors Inc. (the research team) recently conducted a series of fuel economy and in-use
emissions tests of light-duty gasoline vehicles (LDGVs) and class 8b Heavy-Duty Diesel
Vehicles (HDDV-8bs). The purpose of this testing program was to evaluate the performance of
CCT’s combustion enhancer 43 , trade marked as 2ct®, on an LDGV and HDDV-8b truck.
A test procedure based on the TMC 44 /SAE 45 Type II test procedure (SAE J-1321) was
developed and used to evaluate the product’s effectiveness in improving the fuel economy of
the test vehicles. A similar procedure was developed and utilized to evaluate the impact of
2ct® on the exhaust emissions. SAE J-1321 is primarily designed for heavy-duty diesel
vehicles (HDD trucks and buses) and cannot be directly applied to LDGVs. The research team
therefore developed a protocol closely assimilating SAE J-1321 to be used for LDGVs.
To facilitate the tests, fuel consumption in a test vehicle was compared to fuel consumption in
an identical control vehicle before and after 2ct® combustion enhancer treatment at the
recommended dose rate of 1:500 vol/vol. CCT claims that the product will improve fuel
economy and reduce exhaust emissions after two tanks full of treated fuel. For this test, the
43
The client defines its 2ct® combustion enhancer as a petroleum fuels technology comprising hydrocarbon
components that is mixed with fuel to improve the combustion burn, of all grades of petroleum fuel.
44
Technology and Maintenance Council (TMC) of American Trucking Association (ATA).
45
Society of Automotive Engineers (SAE).
45
research team ran the test vehicles for a notional 1,000 miles each to ensure that there was no
question of conditioning not having been achieved. This report deals with the two pertinent test
segments according to SAE J-1321: - untreated baseline testing, and – post treatment. Each
segment of testing consisted of a gravimetric fuel consumption testing followed by emissions
testing using SEMTECH-DS manufactured by Sensors Inc. and Montana-2100 and Axion
manufactured by Clean Air Technology International Inc. (CATI) portable emissions
measurement units.
TEST PROTOCOL
FUEL CONSUMPTION TESTING
SAE J-1321 is currently the only approved standardized testing procedure in the U.S. for
comparing the in-service fuel consumption of two conditions of a test vehicle when the tested
component (in this case a fuel technology) requires a period of time for replacement or
modification (e.g. on-road conditioning). Based on SAE J-1321, fuel consumption can be
measured by using a portable weigh tank method (gravimetric method) or utilizing a fuel flow
meter (flow meter method).
The fuel consumption method determines the overall accuracy achievable with this procedure.
The gravimetric method provides and accuracy of ±1% (i.e. the actual improvement is within
±1% of what is observed). The gravimetric method is by far the most widely used fuel
consumption measurement method because of its relative simplicity and consistency
SAE J-1321 is primarily designed for heavy-duty diesel vehicles (HDD trucks and buses). Due
to this characteristic, it cannot be directly applied to other types of vehicles such as LDGVs.
The research team proposed a series of test protocols for this vehicle type to address this issue.
These protocols closely assimilate SAE J-1321 with some modifications to make them suitable
for LDGVs.
SAE J-1321 46
The Joint TMC/SAE fuel consumption test procedure – Type II – SAE J-1321 is the proposed
test protocol for these vehicle classes. Major elements of the procedure are:
•
•
Two vehicles are used for the test — a control vehicle (“Vehicle C”) and a test vehicle
(“Vehicle T”). Vehicle C is the control vehicle and is not modified in any way during
the entire test and is dedicated to the test until the entire test process is complete. This
includes load, trailer, and driver.
The gravimetric method uses a portable auxiliary tank of at least 16 gallons to measure
the fuel consumption. The tank is topped off and weighed before the test run and
weighed again after the completion of the test run during which the vehicles perform
the same driving pattern.
46
SAE International, Joint TMC/SAE Fuel Consumption Test Procedure – Type II, SAE Surface Vehicle
Recommended Practice J1321, 1986.
46
•
•
The fuel consumption calculations are based on T/C ([vehicle T]/[Vehicle C]) ratios. A
T/C ratio is the ratio of the quantity of fuel consumed by the test vehicle (vehicle T) to
the quantity of fuel consumed by the control vehicle (vehicle C) during one test run.
The testing consists of two sets of tests — baseline and treatment. Each set is composed
of a minimum of three valid T/C ratios according to SAE J-1321.
o Baseline: to establish baseline fuel consumption of the test vehicle running on
untreated fuel (vehicle T); and
o Treatment: to establish the fuel consumption of the test vehicle after
modification.
Modified Test Protocol for Light Duty Gasoline Vehicles.
SAE J-1321 requires using a portable tank of at least 16 gallons, however, this could not be
achieved for LDGVs due to the following characteristics of gasoline vehicles: fuel pump is
located inside the fuel tank; there is a sensor on the fuel pump assembly that sends information
to vehicle’s computer; and a gasoline vapor recovery system is mounted on the fuel tank. To
account for these issues, the original tank of the truck was placed inside the cargo bed of the
truck and was used as an auxiliary tank
After the baseline tests were completed, the test vehicles were each subjected to a period of
approximately 1,000 miles running on the treated fuel. CCT representatives monitored the
conditioning at 250-mile increments and confirmed the completion of conditioning.
TEST PROCEDURE FOR EMISSIONS TESTING
Emissions of total hydrocarbons (THC), carbon monoxide (CO), carbon dioxide (CO2), oxides
of nitrogen (NOx), and particulate matter (PM) were measured using two Portable Emissions
Measurement System (PEMS) units. The SEMTECH-DS was used to measure CO, CO2, and
NOx emissions, and PM emissions were measured using the OEM-2100 Montana system for
the LDGV and the Axion system for the HDDV.
Currently, there is no standard test procedure for on-road emissions measurement. Therefore, a
test procedure was developed by the research team to capture on-highway operational
conditions. This procedure follows the preparation and calculation methods of J-1321.
The emissions testing was performed directly after completing the fuel efficiency testing
Two sets of tests were performed — baseline and treatment. Each set was composed of a
minimum of three valid emissions reading: Baseline – to establish baseline emissions rates of
the test vehicle running on untreated fuel (vehicle T); and Treatment – to establish the
emissions rate of the test vehicle after treatment.
TESTING INFORMATION
TEST FACILITY
The test was conducted at the Pecos Research and Testing Center (RTC) outside Pecos, Texas.
The 5,800-acres facility has a nine-mile, three-lane circular high speed track for speeds up to
47
200 mph. Figure B.1 shows the location of the Pecos facility as well as an aerial view of the
test tracks.
Figure B.1. Location and Layout of the Test Track.
TEST FUELS
Regular gasoline and diesel was purchased and stored in the Pecos facility prior to the testing.
These fuels were used as “base fuel.” A specific portion of these fuels were mixed with 2ct®
combustion enhancer at the recommended ratio of 1:500 (volume-to-volume) and were used as
“treated fuel.” The mixing was performed by representatives of TTI under supervision of CCT.
Treated fuel was used for conditioning and treatment testing.
TEST VEHICLES
Two 2005 model year Toyota Tacoma trucks and two 2008 International / Pro Star 1351
HDDVs were selected for testing.
MODIFICATIONS TO TEST VEHICLE
The following modifications were made to the Toyota Tacoma test vehicle’s exhaust line
(Vehicle T) and emissions sampling procedure for this vehicle in order to demonstrate that
2ct® is a combustion enhancer:
- The oxygen sensor on the test vehicle was disabled. This was performed to make the
engine work under “real conditions” by preventing the engine’s computer from modifying
the combustion condition through changing the fuel flow based on the inputs of oxygen
sensor. The oxygen sensor was disabled for the entire duration of fuel consumption and
emissions testing.
48
- For the test vehicle, the “engine-out” emissions sample was used instead of the regular
“tailpipe-out” sample. This was performed to eliminate the effect of the catalytic converter
on the emissions of test vehicle. The gaseous emissions sample line was connected to the
exhaust line before the catalytic converter. The PM emissions sample was taken from the
tailpipe.
Note that the above modifications were applied only to test vehicle (Vehicle T). The control
vehicle (Vehicle C) was used in its original state (unmodified state) for the entire duration of
the study and the emissions samples were all tailpipe-out samples.
TEST CARGO
According to SAE J-1321, the vehicles under test should have a cargo with weights
representative of the fleet operations and within the capability of the vehicles. To comply with
this criterion, both LDGV control and test vehicles were loaded with QUIKRETE® cement
bags to reach the gross vehicle weight of 3,820 lbs, and both HDDVs were loaded with
concrete barriers to reach the gross vehicle weight of 68,000 lbs.
DRIVE CYCLES
Both control and test vehicles were tested according to the explained test procedures. In order
to maintain the consistency between test runs, the vehicles were driven to fixed drive cycles at
constant speeds and distances. Prior to testing, a warm-up driving period of 45 miles was
executed for all vehicles.
TEST DRIVE CYCLES
A separate drive cycle was developed for emissions measurement components for each of the
gasoline and diesel tests.
ANALYSIS DRIVE CYCLE
A synthetic drive cycle was used for emissions data analysis for each of the gasoline and diesel
tests.
RESULTS
FUEL CONSUMPTION
The T/C ratios for all test runs were calculated and the first three ratios that fell within the SAE
J-1321 prescribed 2 percent filtering band were used to compute an average value representing
each segment of testing.
GASOLINE
DIESEL
FUEL SAVED
6.8%
12.1%
IMPROVEMENT
7.3%
13.7%
49
Results show that the addition of 2ct® combustion enhancer to the base fuels produced an
improvement of 7.3 percent under the modified J1321 test procedure and test vehicle
modification (i.e. disabled oxygen sensor) for the gasoline test and 13.7 percent for the diesel
test. The fuel saved and improvement values are calculated according to SAE J-1321 as
following:
% Fuel Saved
= (Ave. Baseline T/C – Ave. Treatment T/C) ÷ Ave. Baseline T/C
% Improvement = (Ave. Baseline T/C – Ave. Treatment T/C) ÷ Ave. Treatment T/C
[2]
[3]
EMISSIONS
The improvement percentages are calculated according to the J-1321 calculation method.
Positive improvement values mean a decrease in the total emissions for the cycle while a
negative value indicates an increase of the pollutant.
GASOLINE
DIESEL
CO2
6.9%
5.4%
CO
27.1%
-6.6%
NOx
-13.3%
-2.1%
Results show a statistically significant improvement of 6.9 and 5.4 percent respectively for
CO2 emissions. The results also indicate a statistically significant 27.1 percent improvement
for CO emissions for gasoline and a statistically insignificant increase of 6.6% for diesel. The
results show a 13 and 2 percent increase in NOx emissions of the already low readings for the
post 2007 Class 8b trucks. These differences are statistically significant at the 95 percent
degree of confidence level for gasoline and are not statistically significant for diesel.
From the gasoline emissions tests PM emissions differences were found to be statistically
insignificant. Both diesel vehicles were equipped with Exhaust Gas Recirculation (EGR) and
Diesel Particulate Filters (DPF). EGR is a NOx emissions control device working by recirculating a portion of exhaust gas back to the engine cylinders. EGR can reduce NOx
emissions as high as 50 percent. DPF is a device developed to reduce PM emissions in diesel
engines’ exhaust gases. The PM emissions rates were found to be very low and close to the
detection limit of Axion emissions measurement unit. Because of this, the collected data were
inconclusive and not reported here.
A full copy of the report can be obtained from: [email protected]
50

SmartWay Applications for Drayage Trucks

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